Typically electronic devices are cooled by means of passive natural radiation from an associated heat sink device, usually constructed of aluminum. Some high powered electronic devices, however, generate very large amounts of heat and cannot be adequately cooled by passively radiating heat sinks. For such devices specialized cold plates are provided which can absorb large amounts of excess heat and prevent overheating.
Cold plates are generally constructed of heat conducting metallic materials and are mounted adjacent to the heat producing components. A heat transporting or absorbing fluid is routed through heat transfer fins or passages within or adjacent to the cold plate so as to remove the excess heat generated by the heat producing components.
When heat producing electronic devices are carried aboard aircraft the heat absorbing fluid is generally air. Cool air is ducted past the cold plate from an external port which is exposed to air flowing past the aircraft, unfortunately, this does not always provide sufficent cooling. Inadequate cooling occurs when either there is insufficient cool air available to cool the cold plate or when high aircraft speeds result in a ram effect which heats the air passing over the aircraft surfaces so that the air is too warm for useful cooling.
Various devices have therefore been used to cool airborne electronics, an example of one can be found in U.S. Pat. No. 3,776,305 to Simmons. The device disclosed in the Simmons patent uses a liquid coolant circulated through cold plates to cool adjacent electronic devices. The subsequently heated liquid coolant is then circulated either to a cooling bath of a secondary liquid or to an air cooled heat exchange area. When cool air is unavailable and the coolant temperature is at its highest, the secondary liquid from the cooling bath undergoes a phase change from liquid to vapor and absorbs additional heat from the circulating coolant. The Simmons device is therefore relatively complex and bulky since it provides for two separate liquid media, two separate heat exchangers and a coolant circulator pump. Such large units are somewhat disadvantageous on aircraft where light weight and minaturization are of critical importance.
In view of the above it is an object of this invention to provide a light weight and compact heat transfer device capable of providing adequate cooling for heat dissipating components independent of the availability of cooling air.